Method of producing analgesia.



F. K.'VREELAND.

METHOD OF PRODUCING AINALGESIA.

APPLICATION FILED JUNE 25, I914.

Patented Feb. 26, 1918.

Witnesses I Attorneys.

, APPARATUS COMPANY, OF NEW :YORK,

To whom it may concern; 1 Be it known that I, FREDERICK K. VREE- LAND, a citizen of the United States, residing at Montclair, in the county of Essex and State of New Jersey, have invented a certain new and useful Method of Producing Anal-l gesia', of which the following' is a'specifica;

. current;

' dental nerves; and 1 tlon. I p invention relates to the production of anesthesia. or analgesia by means of electric currents, and while it has been especiallyi developed for the production of analgesia in the teeth, so that they may be operated upon without pain to the patient, it is capable of effective use for producinganalgesia for other surgical work. f I r It is well known that under favorable conditions a suitable electrical current may pro'- duce analgesia. or render the bodily tissues insensitive to pain] Heretofore, however, any practical attemptsto produce analgesia, by means of electric current have been limeited in scope, and in most cases altogether impracticable, because the currents .used were not Suitable for the purpose and the method of applying the current was-faulty or inadequate. For these reasons the eradication of pain by the application of electric currents has not been heretoforecompletelyrealized, and infact the current itself often has been a source of pain. In the practice of the present invention the sensitiveness of the nerves and tissues to pain is completely eliminated when the, current is used,'and its modes of application are of sucha character that it maybe applied even-tothe most excessively sensitive tissues of teeth without discomfort. to the patient, a

In order that the invention may be better understood attention is directed to, the accompanyingldrawing's, forming part of this specification, and in which,

Figures 1, 2 and 3 show the wave formof current used;

Fig. 4; is a diagram showing the circuit connections of the preferred arrangement for generating, controlling and applying the" Figs. 5'and Qillu strate devices for applying the current exteriorly to they-principal Figs. 7, 8 and 9 are detail views showing various devices for applying the current to individual teeth.

tically constant amplitude.

maybe a pure alternating current, as shown N. v. a conrona'rron or new YonK.

Mn'rnon orrnonucms nnerensm; f

. Specification of Letters Patent. Patent gdl Feb, 26, 191%,, Application-filed Jane 25,1914. Seria1 No.84 1,199'.

high frequency sinusoidal current of prac- This. current m Fig. 1, or a'unidirectional pulsating cur-.

rent, as shown in Fig. 2, .or a reversing pulsatlng current, asshown in Fig. The current wave forms shown in Figs 2 and 3 may .be considered as a result of superimposing a pure alternating current upon'a direct current. All three wave forms are, effective, but for convenience Iprefer usually to employ the'simple alternating current of pure sine wave form, shown in Fig. 1. The character and frequency of the current used to produce anesthesia or analgesia are highly important, as 1 have determined by aotual able or is not correctly applied, the'analgesia will not be complete, or the current itself will producediscomfort, or both. For

' demonstration. If the current is not 'suitexample, if a direct current of moderate 'intensity is suddenly applied tothe body it produces a twinge at the moment of application, which sensation quickly passes away, since the nerves involved apparently accom- -1 nodate themselves to the current. If such a current is gradually applied it gives no sen sation, but any sudden increase is felt unpleasantly. In either case analgesia is not produced. Periodically repeated applications of such a current produce a painful successionof twinges, or if the applications are rapid, apra ctically continuous pain. If this rapidity of the applications is suflicient, some analgesiamay be produced. A sinusoidal alternating current of the same maximum intensity and applied with the same frequency as in the last example referred to (i. e. the same number of alternations or impulses per second) produces a less painful effect than the intermittent direct current, but with ordinary frequencies the shock of successive impulses. isvery unpleasant, and under some conditions extremely painful.

' As the frequency of the alternating current increases, vthe shock gradually diminishes,

and finally disappears. By applying a high frequency sinusoidal current of the character and in the manner herein set forth. the

full analgesic effect is produced without painful effect of the current itself, even fore for therape tic purposes, but the frequencies employe have been low, usually no .more than from 10 to- 60 cycles per second.

the mode of application is suitable, the

nerves are incapable of responding to the successive impulses, and the sensation of shock is completely eliminated. If such a current of suitable magnitude is applied to a nerve by suitable means it apparently has the effect of inhibiting the'power of the nerve to transmit the sensation of pain, and hence the tissues which the nerve controls may be cut or otherwise operated upon without discomfort to the patient, and sometimes without actual consciousness of the fact.

'Usually, however, the sensation of touch is not completely eliminated, and hencethe effect is perhaps more accurately described as an analgesia or absence of pain, rather than an anesthesia or absence of sensation.

The current itself, when properly applied, does not produce painful or disagreeable sensations. In many'cases, particularly of dental work, it has been observed that the patient is sometimes conscious of a numbness of the tissues affected; in other cases there is apparently a sensation of slight warmth, and in others'a slight cooling sensation, but there has been an entire absence of the shock or painful effect that has accompanied previous attempts-at electric anesthesia. highly important that the amplitude of the current-be kept relatively uniform, since any irregularities or sudden fluctuations of the current are ob ectionable and cause discomfort to the pai in the current strength or amplitude should be made gradually. It is also important that the current shall have a high frequency,

and in practice I prefer to employ a frequency of between 1,000 and 2,000 cycles per second. Satisfactory'analgesia may beobtained with lower frequencies, but as the frequency is diminished the sensation of the current increases. On the other hand, good results may be secured by the use of higher frequencies, but for convenience in generating and handling the current, I prefer not to exceed the limit named.

Another feature of the current employed is its pure sine wave form. The. smooth and are not of constant. amplitude, but

It isient. All necessary changes the current as a high fre uency sinusoidal current I am not contemp atin the excess s1ve frequencles sometimes use for therapeutlc purposes when employing a spark oscillator of the Tesla or Oudin type. Such currents may have a frequency of a million or more cycles per second,-or in other words 500 times the frequency that I employ; they are not continuous, but intermittent; the wave form is not sinusoidal; the oscillations are strongly damped, and they produce no anesthetic effect. For generating the high K frequency sinusoidal currents of constant amplitude, I prefer to employ the sine wave oscillator described in my United States Patents Nos. 829,447 and 829,934 dated August 28, 1906. Such an apparatus is shown diagrammatically in Fig. 4. The high frequency sinusoidal currents are setup in an oscillating circuit 12-1, including the field coils 11 and condenser L. A secondary coil 3 is mounted in inductive relation to one or both of the field coils .l1, and

the electromotive force thus induced in the secondary coil is employed to set up the current applied to the patient. The secondary coil 3 may be and preferably is movable with respect to the field coils 1, 1 for the purpose of adjusting the 'electromotive force.

In series with the coil 3 is an adjustable rheostat or equivalent impedance 4 which controls the intensity of the secondary circuit. The secondary circuit is completed through'ele'ctrodes 5, 6 by which the current is applied to the patients body. A switch is shown in the secondary circuit.

The arrangement shown in Fig. 4 is not the only one which may be employed, and in fact any suitable arrangement may be used by which sinusoidal currents of the necessary high frequency and practically constant amplitude may be generated. Furthermore, it will be obvious that suitable means for controlling the current may be substituted for the movable coil 3 and rheostat 4. In applying the. current to the pa-- 4 is set to a high resistance and the electromotive force is applied to the patient by closing the switch "71or by moving the'coil 3 into inductive relation'with the 'coils 1, 1.

the current flowing through the pa'tientxis not suflicient-to produce an unpleasant sen sation at the momentof completing the c1r.-'

wit. The current is jthengradually increasedby cutting outresistance 4 or v1ncreasing the electro-motiveforcein coil 3,

a or both, until* the desired analgesia is produced. It is desirable to increase the current intensity gradually, since any sudden variation orirregularity. may produce an unpleasant sensation.

conscious of the current, 'evenwhen it has reached the-magnitude required for complete The application of-eurrent to' analgesia the pat ent is. continued aslong as analgesia is required. When the current is shut off the normalfunctionsof the nerves and sensie tlveness of the tlssues return almost 1mm'ediatel'y. If analgesia is required for aconsiderablelength of time it'may be necessary *complishedby cutting to increase'the intensity of the current from time to time as the nerves beginto accustom 30 themselves to the current. This may be acin the rheostat lfwhen required.

In order to reduce'any fluctuations in the current app-lied to the patient due to variations of the contact resistance at the electrodes, or to other causes,- it is'de'sirable to make the resistance 4 large with respect tothe resistance of the external oireuit. The electromotive force induced in the coil 3 should be correspondingly large, so that the greater part of the electromotive force will be consumed in the resistance land the rel-, atively' smaller remainder applied to the.

patient. The apparatus then operates praetically as a constant current device, and accidental fluctuations ofthecurrent, which mightcause discomfortto the patient, are avoided. The resistance of the patients body, including the-contact resistance at the electrodes, is usually between 1000 and 10,000 ohms. It is desirable therefore that the rheostat 4 should have a maximum resistance of from 50,000 to several hundred thousand ohms, and its range of. adjustment should be such that when the maximum current "is flowing its-resistance is still large compared with the resistance of the external circuit. I

The mode of application of the current to the patient may be varied to suit the requirements of the case, and successful. results to a certain extent will depend upon the ingenuity and resourcefulness ofthe operator in applying the electrodes in such When the current 'is applied gradually the patient} experiences no discomfort and may in fact be entirely unout further resistance afway as to secure the maximum efiect.

Where general anesthesia is required the electrodesshould be so applied that the current traverses the brainor some portion of the spinal cord, For producing local anes-- 'thesiaor analgesia ina restricted portion of the body-it is sufficient to apply the current tothe "sensory nerve or nerves to be anesthetized, I prefer to apply the active electrode orfelectrodes 5, at some point where the nerve or nerves lie close to the surface,

in such a-manner that the current when enterin'g the body will traverse the nerve tissue, thus inhibiting, its function of transmitting the sensation of pain. The electrode 6 through which the-circuit is completed may be neutral and applied to the jbody atsome convenient point, .or 1t also may be active and applied in the neighborhood of a nerveornerve trunk. Where a multiplicity. of electrodes 5 are employed each one should havea separate resistance or equivalent impedance l'to insure aproper distribution of-the current. In general it is desirable that the active electrodes 5 be small to concentrate the current at the desired point, while the neutral electrode,

when used, is made relatively large, to dis-,

tribute and reduce the concentration of'the current. The analgesic elfect. depends upon the concentration of the current in, the nerve tissue rather than on its aggregate amount. Where the region to beanesthetized is controlled by a plurality of nerves, or nerve trunks, a plurality of electrodes 5 or 6 are employed, each applied to its respective nerve or nerve trunk at an appropriate pointbetween the region to be treated and the brain or spinal cord.

Where the invention is used to produce analgesia in the teeth the current should-be applied to some portion of thedental nerve or nerves supplying the tooth or teeth to be operated upon. It is possible to anesthet ize a number of teeth simultaneously,- by 1 applying an electrode 'to the nerve-at some distance from the teeth. There are several places at which such electrodes may properly be applied. The two halves of the lower jaw are supplied respectively by the right and left inferior maxillary nerves. Each of these nerves approaches-the outer surface of the chin at the point where it passes through the mental foramen. A small electrode applied immediately over the mental foramen on either side willlead the responding teeth on the lower jaw. In Fig.

I show an arrangement of the electrodes penetrate the skull respectively through thecurrent to the nerve and anesthetize the cori right and left infraorbital foramen, which are located at opposite sides of the nose below the eye. Electrodes applied at one or both of these points will control the teeth of the upper jaw; and in Fig. 6 I show an arrangement of electrodes for this purpose.

The dental nerves may also be reached from points in the back of the mouth. It is usually preferable, however, to apply the current at the external points above mentioned.

I have found in practice that under ordinary conditions greater convenience is secured when the current is applied only to the particular tooth which is to be operated upon. To this end an electrode may be ap plied to the surface of the gum near the root of the tooth, on either the outside or the inside of the jaw. Or, two electrodes may be employed, one on the outside and one on the inside, so that the current passes from one to the other through the jaw tissue and thus traverses the nerve supplying the tooth. Such electrodes may be held in place by rubber suction cups 9, one of which is shown in Fig. 7 or they may be supportedfrom a clamp attached to an adjacent tooth and supporting an adjustable arm carryingat its extremity an electrode, as shown in. Fig. 8.

The best results, however, are obtained when the current is applied directly to the tissue of the tooth, and it may be successfully applied in several different ways. A convenient method is to spring a metallic clamp over the tooth near the gum and attach a conductingwire to this clamp, which serves as an electrode. The clamp should be insulated except where it touches the tooth, by suitable insulating covering or by a rubber dam stretched over the tooth between the clamp and the gum.

The clamp used may be one well known to dentists, consisting of a pair of jaws connected by a stiff spring. Such an electrode, however, is sometimes objectionable because of the rigidity of the jaws, and unless the jaws are accurately fitted to the teeth they may make contact at only four points. The current will then be concentrated at these four points, and the current density in the tooth tissue may thus become so high as to cause pain or discomfort to the patient before the current is strong enough to completely inhibit the functions of the nerve. To avoid this difiiculty I employ an electrode of the form shown in Fig. 9, in which the jaws which embrace the tooth are in the.

form of elastic forks betweenthe points of which fine wires are stretched like bow strings. Such an electrode will adapt itself to the contour of the tooth and will establish a good contact of sufii'cient area to prevent undue concentration of the current.

It is sometimes inconvenient to apply an electrode at the base of the tooth. Under such circumstances the electrode may be applied at any desired portion of the tooth surf ce. The electrode for this purpose may cons st of a mass of conducting cement stuck to the tooth surface, or an adjustable electrode may be employed, such as that shown in Fig. 8. The electrode proper consists in a mass of wet cotton, or other conducting material, contained in a cup of soft rubber or other insulating material and connected to a wire or conducting lead. -This cup is supported by a double-jointed arm, having "pivots allowing it to move in any direction in a given plane. The supporting arm is made of spring metal or other elastic material to hold the electrode in firm contact with the tooth. The end pivot of the supporting arm is carried by a saddle, which is fixed adjustably to the bow of a clamp adapted to be sprung over the tooth. The saddle is arranged to be adjustable at any point of the bow so as to permit angular adjustment of the saddle and the arm which it carries. The clamp is applied to a tooth adjacent or near to the one to be operated upon, and the electrode cup .is capable of adjustment to make contact at any desired point of the tooth surface. I prefer to construct the supporting arm wholly or in part of insulating material, so that ample creeping space may be provided to prevent surface leakage of the current.

Whatever mode of attachment is employed for the electrode 5, the return electrode 6 mav be applied to any convenient portionof the patients body, being grasped for example in the patients hand or being applied as a plate or pad to the patients cheek. Preferably for dental work this electrode 6 is a small metal disk slipped into the patients mouth. Such an electrode, by making contact with the moist mucous membrane, eliminates .to a large extent the skin contact resistance.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. The method of producing complete or partial anesthesia or analgesia which consists in subjecting the nerve, or nerve center or tissues controlled thereby, to the effect of electric current of high frequency and substantially uniform amplitude, as set forth.

2. The method of producing complete or partial anesthesia or analgesia which consists in subjecting the nerve, or nerve center or tissues controlled thereby, to a current having the form of a sine wave of high frequency and substantially uniform amplitude, as set forth.

3. The method of producing complete or partial anesthesia or analgesia which consists in subjecting thenerve, or nerve center memes M or tissues controlled thereby,' to a current having a frequency in excess of 1000 cycles per second, and of substantially uniform amplitude,-as set forth.

4. The method of producing complete or p'artialanesthesia or analgesia which consists in subjecting the nerve, or nerve center or tissues controlled thereby, to the effect of electric current of high frequency'and substantially uniform amplitude, the current be- 10 ingvgradually increased in amplitude until the desired effect is secured, as set forth.

This specification signed and witnessed this twenty-second day of J une; 1914.

FREDERICK 1K. VREELAND. Witnesses: v

FRANK C. DYER, ANNA E. RnN'roN. 

